So what? That's not very relevant to the conversation. His point was Rashad has never fought at 185. Edgar hasn't fought at 145, what does him defending the belt at 155 have to do with him never fighting at 145?
It shows a history of consistent performance at the highest levels. Whether they can carry those skills and so forth to another weight class with the same results is a valid question, but it shows that they at least have those skills & attributes in the first place. Aldo, Edgar, GSP, Silva, and Jones are all proven fighters at the highest levels. Rashad is not. That is the difference.